Afterwards, he looks down.
The room's almost dark, the blinds down, the lights off, but even before the serum Steve's always had good night vision. He'd been so careful to keep his eyes screwed closed, his hands to himself except when - Tony had flinched at the touch of his knuckles, and after that - he'd even held his breath, until he couldn't.
Afterwards, he looks down, and Tony's skin is pale against the soft darkness of his sheets. The strong curves of his thighs, the arched hollow of his lower back, the single crescent fold under his buttocks and the fine, soft spring of the hair on the back of his legs could almost be a sketch in charcoal, but the silver trail of Steve's come on his inner thighs has a translucent sheen no artist could replicate. It's almost, in the abstract, beautiful.
"Jarvis," Tony says sharply.
Steve snatches his bathrobe back into place and flees.
After the debrief, Natasha's waiting for Steve in the gym.
Tony pulls off and says, hoarse, "If I can, you can." His hand - Tony's clever fingers with their knotted knuckles and stains and manicured nails - his hand cradles Steve's balls, the pressure breathtakingly just shy of pain, and his thumb, wet, is tucked up behind them.
Steve can't stop himself. He says, "This isn't what I - this isn't how -" and disregarding every resolution he's ever made, his fingertips brush against the softened spikes of Tony's hair.
"Right at this moment I don't give a fuck about your apple pie scruples, Cap," says Tony, and for the love of Mike his thumb is pressing against Steve's ass and his mouth is - Tony's mouth - Tony -
Steve thought even working girls spat, but Tony swallows.
It takes fifteen minutes before Steve can get hard. He won't let Tony touch him.
Tony says. "What the hell do you need? Flowers?" The shape of his shoulders against the pillow is a hunched silhouette. "Porn?" He's holding his own ass open, shockingly, gloriously unembarrassed.
Steve punches the words out with the thrust of his cock, quick as he can, clinical, meaningless, awful - "Tony-"
He pulls out the second he comes. Tony says nothing.
"Um," Steve says. "I-"
"Oh for christ's sake stick it in," says Tony.
Under him, Tony breathes out, heavy, almost amused. "That's one way to look at it," he says.
"I'd like to," Steve says. He lets his thumb stroke Tony's skin, curls over just far enough to let his dog tags skim Tony's back, rolls his hips and feels Tony's ass tighten. Almost, Tony pushes back. "Look. Now. See you, I mean."
"Rogers," Tony says, eventually. "Be hard to kid yourself you're in bed with your best girl if the light's on."
"I know where I am," Steve says. He ducks a little further, lets himself say against Tony's shoulder, "Please."
"Lights," Tony says.
Steve comes as fast as he can force his body into compliance, but afterwards, he lets himself stay, just a moment, just to see the way the sweat on Tony's shoulder gleams, the stifled, strained lift of his breathing and the clench of his fisted hands and the flush of color on his cheeks. Tony's lower lip is a deep red, as if he's bitten it, and his eyes are screwed closed. If they were lovers - if they were lovers, Steve would tuck his forehead down into the strong arch of Tony's neck, run a hand underneath his belly and catch Tony's cock in his fingers, find it hard and wet and match pleasure with pleasure. If they were lovers, Steve would stay here, right here, curled into the sun-heated metal smell of Tony's skin and his strength, the deft gentleness of his hands and the pomaded softening spikes of his hair. He'd know what Tony's beard felt like on his own skin, would have closed his mouth around Tony's cock and felt it harden on his tongue, would know the taste of Tony's come -
"Steve," Tony says. "Steve. You want me to jerk off while you're still here?"
"Yeah," says Steve, and rolls them both over onto their sides. He masturbates in the shower, Wednesday, Saturday and Sunday mornings, missions allowing, but Tony's shameless. Tony's probably done this... Steve tangles their hands together and drags them down, over Tony's chest and the small secret softness of his belly to his cock, the skin so velvet smooth under their mingled touch but so hot, and Tony's not flaccid but half-hard and hardening fast.
"Shit," Tony breathes, his head back and his fingers tightening. "Oh shit. Hell."
"What? Did I, is this-"
"Oh God, don't stop," says Tony, and his fingers are shaking, his shoulders tight, his ass pressing back in a complicated, twisting arch that tugs and pulls and ripples around Steve's own cock, wetly hardening all over again. "Steve. Oh, God, Steve, holy shit, fuck me."
Tony comes on the tenth stroke, and Steve lasts three more. He pants damply into Tony's shoulder, their hands still clasped and wet with Tony's come. He should say something. In just a moment. Now.
But Tony's fingers are lax and his body hunched into the mattress, uncommunicative.
Afterwards, Tony looks almost better. He sleeps most of the night, stumbles into breakfast with his hair tousled and his feet bare, the bags under his eyes almost gone and his skin looking tanned rather than sallow. Natasha drops Steve the ghost of a wink and a smile so small it's almost a secret, and Iron Man kicks ass that afternoon, keeping up a running commentary on the comms that cracks Steve up four separate times, once mid-swing. Captain America, on open comms, doesn't even say a word about protocol.
That night, Steve screws his courage to the sticking point and triple-checks the lock on his door. He has to clear his throat twice. "Jarvis?"
Tony's eyes are wider than Steve's ever seen them, his mouth open. His voice cracks. "Ste-" He swallows, and runs the tip of his tongue over his lower lip, and manages, "Yes. Oh fuck hell to the yes."
"Glad we got that clear," Steve says, so relieved he's smiling, and bends down. "Kissing now," he says, two fingers deep, and Tony arches up into his hands willing and wanton and noisy and perfect.